gpg: Fix key generation with existing key from card.
* g10/keygen.c (ask_algo): Fix condition. Continue the loop when failure.
- Fixes-commit: 6022f10da39e512b5b3fed3869fd6579d954090c
- GnuPG-bug-id: T7309, T7457
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>